Telephonic repeater



C. ROBINSON AND R. IVI. CHAMNEY.

TELEPHONIC REPEATER.

APPucA'noN flu-u Nov. la, 1919.

6 SHEETS-SHEET I.

1,429,634 Y memedsept. 19,1922.

C. ROBINSON AND R.iVl. CHAVINEY.

TELEPHONIC HEPEATER.

APPLICATION FILED Nov. I8, I9I9.

Ipqggpgqcu wanted Sept. III, M222 e SHEETS-SHEET 2.

c. ROBINSON AND n. m. CHM/miv.

' TELEFHONICAREPEATER.

APPLICAION FILED NOV- I8. '919.

Mw Pat/mmm m9319222,

6 SHEETS-SHEET 3.

C. ROBINSON AND R.. IVI. CHAMNEY.

TELPHONIC REPEATER.

APPLICAHON FILED Nov.18,1919.

' '1&429963@ Patented Sept. 99 11922.,

6 SHEETS-SHEET 5.

- C. ROBINSON AND R. IVI. CHAIVINEY.

TELEPHONIC REPEATER.

APPLlcArxQN man Nov18,19\9.

Patentedept. 19, i922,

6 SHEETS-SHEET 6.

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Application tiled November te, 19N. serial No. 338,381.

.To all 'whom it may con/cera:

Be it known that we, Cuantas Ronrn'sou und Roaman MARTIN CHAMNnr, both subjects of the Kin of England, residin re spectively, at Reigate, in Surrey, Eng and, and London, En and, have invented certain new and useful mprovements in Telephonie Repeaters, of which the following is a speciiication.-

This invention relatesV to telephonie re-v peaters of thev transformer type comprising two sets of speakingline-windings mag-v half of the differential winding being con= nected to each half of the circuit or to one half of the circuitand a balancing clrc'uit.

the centre point of the differential winding of the input transformer. lin this arrangement, if the impedances on each side of the input transformer are equal, the magnied currents from the output transformer will divide equally between the diderential windings ofy the input transformer and will not f have the edect upon the repeater of tending to produce reaction or howling 'llhis invention has for its object to simplify the construction of telephonie repeaters of the type referred to and, in one embodiment, to provide a repeater comprising one transformer only.

The expression line-windings isused f herein to cover windings included either in an actual line-circuit or in an artificial or balancing line-circuit.

Conveniently, a doublaamplier repeater 'according to the invention and comprising two transformers may vhave the vlatter so cross connected that the magnified current from the amplifier fed by the one transformer is supplied to the other transformer,

and one of the line-windings of each transformer is connected to an artificial line. i

lln the accompanying drawings- Figures 1,2, 3 and 4 are diagrams illusrating various embodiments of this invenion,

Figure 5 is a diagram showing only the transformer arrangements for a modied embodiment of this invention,

Figure 6 is a longitudinal section, f `lliigure 7 is a transverse section, and

Figure 8 a. plan illustrating one method I of constructing a transformer in with this invention.

Referring to Figure 1 which illustrates one method of carrying the invention into practice with a single-amplifier telephonie repeater .comprising one transformer only,

accordance the .iron core A of the transformer is built' up of stampings, each having three limbs, i. e. one centre and two outer limbs magnetically in parallel with one another. The outer limbs are wound each with a linewindi B, B1, and on the centre limb is wound a generator or input Winding C, which is connected to one side of an ampli- -ner, for example to the grid circuit Dhof a thermionic valve D. The outer'limbs are also Wound each with one half of a booster winding in two halves E, E1 connected in series with one another and having the three ends of the pair connected to the anode circuit of the valve D. 'llhe line-windings B,

'B1 are equal and are connected to the up and down lines respectively.

The operation of this single-amplifier. repeater is as follows Speech currents passing through the oneline winding, say B, induce variations of the potential ofthe grid D1 through the generator winding C. This causes variations of the discharge or amplified current passing through the two halves E, E1 of the booster Winding, which in turn induce mag, niied currents in both line-circuits. The magneto motive forces of the two halves E, 1 are equal and so far as their action alone is concerned, they set up no difference of magnetic potentials across the limb carrying the input winding C.

lf, therefore', the impedanoes line circuits are equal, none of the dun due of the two dii lill@ to the amplified current in the booster winding E, E1 will ass through the generator winding C whic 1 feeds the grid. The operation is similar in the case of s eech currents traversing the other line-win ino.

Referring to Figure 2 which illustrates a double-amplifier repeater according 'to this invention, two transformers, each similar to that described above, are used. The cores` A. generatorwindings C, amplifier D, linewinding B and booster winding E are the same as before. ln this case,l however, an artificial line or a balancing circuit F, F1, represented as having resistance and capacity, takes the place of one line in'each transformer. and the anode circuit of the up valve is connected to the booster windings E2., E2 of the down transformer, while the anode circuit of the down valve is connected to the booster windings E, E1 of the up transformer. l

The invention is also applicable to the telephone systems described in the British Patents Nos. 131113 and 131114.

Referring to Figure 3, which shows an arrangement corresponding tov that described in the British Patent No. 131113, the oneline windin B, preferabl in series with a condenser is connecte in shunt across the telephone line. A suitable balancing circuit F is connected across the other linewinding. The opration of this arrangement is similar to that of the single-ampli fier repeater described above.

Referring to Figure 4, which illustrates an arrangement corresponding to the telep phone system described in theBritish Pat- Figure 1.

ent No. 131114:, the one-line winding is divided into two equal parts B2, B4, which are connected one 1n each line of the telephone circuit. A suitable balancing circuit F is connected across the other line-winding, which is also divided into two equal parts F1 and F2. The other elements of .the sys-` tem are the same as before. The operation of this repeater is also similar to that of the single-amplifier repeater described with reference tol Figure 1.

Figure 5 s'lliows .the application of our invention to -provide a. phantom-circuit superposed on two side circuits, all three cir-- cuits being relayed. L1, L2 represent the up and down lines of one circuit connected to the line-windings of the trans.- former S1. L3 and L4 represent the lines of a second circuit connected to the line-windings of the transformer S2. The line-windin of the transformers S1, S2 are wound direrentially, and centre points are con nected to a third transformer S2. An am plifyingvalve is connected to each ofthe transformers S1,'S2 and S3 as shown in These lconnections are omitted fromr Figure '5 for the sake of clearness exceptA to the lower transformer S2. The' 4acteristics' of 4the lcircuit.

arrangement shown as ap lied to transformer S3 is merely dup icated for they transformers S1 and S2, the arrangement being in each case the same as shown in Figure 1 as far as the valve' D is concerned. 70 By means of this arrangement, speech currents in the circuit L1 or L2 are amplified by the valve connected to the transformer i, S1; those in the circuit La or L'1 are amplified by the valve connected to the transformer S2, while those in the phantom-g circuit are amplified by the valve connected to the transformer S3. If the lines L1, L2,' La and L4 and also the differential windings of the transformers are correctly bal- 80 anced, there will be no interference between the three circuits.

Referring to Figures 6, 7 land 8, E-shaped stampings "A of suitable magnetic material, such as stalloy, are placed so as to form 85. a magnetic core which is continuous with the exception of two narrow air-gaps H inthe outer limbs of the core. This stalloy asanalyzed by Prof. Turner in the Umversity of Birmingham may comprise .03.90 carbon, 3.4 silicon, .04 sulphur, .01 phosphorus, .32 manganese and 96.2 iron. The width of these gaps is secured at the right value by means of a non-magnetic spacingpiece. The `bobbins J surrounding the outer 915 limbs of the core" are wound with the lineand anode-windings. The bobbin J1 on the centre limb of the core carries the gridwinding. A

The stampings are lirmlyclamped be- .10@ tween wood blocks 'K by means ofthe bolts and nuts K1. A. sheet-iron case K2 encloses the transformer, so that when arranged in banks each shall be shielded from stray fields. The'connections to the windings are 105 taken through the base M to the connection tags M1 mounted in the ebonite block M2.

The number of turns in the. windings used depends upon the characteristics of thermionic valve and also upon the char- 310 For unloaded underground circuit and a valve having an internal impedance of about 26,000 ohms. the following windings are suitable:-

Grid windin'g 16,000 turns. l Anode winding- 2 X 3,500 turns. Line. windings- 2 X 700 turns.

Maaate limb, respectively, of the transformer may netic core structure comprisingthree cores magnetically in parallel with one another between two yokes common to the two sets of concurrent ends of the cores, two linewindings, one upon each of two said cores, a booster winding in two equal halves in series to assist one another, each mounted upon one of the said two cores which carry line-windings and having their two freeIl ends connected to one operative side of` the said current-magnifying device, a generator winding mounted on the third said core of the said Acore structure, and connected to the other operative side of the current-magnifyinv' device, substantially as described.

2.alln a telephonie repeater, the combination of two current-magnifying devices, two.

magnetic core structures, each comprising three cores magnetically in parallel with one another between two yokes common to 4the two sets of concurrent ends or the cores,

two line-windings, one upon each of two coresA ot the one said core structure, two line-,windings one upon each of two cores of the other said core structure, a booster winding in two equal halves in series connected to assist one another, each said halt mounted upon one of the two cores which carry line-windings on the one magnetic core structure and having their two tree ends connected to one operatlve side of one said current-magnifying device, a similar booster winding on the corresponding two cores of the other vcore structure and having its free ends connected to the corresponding operative side ot the current-magnifying device.,

two generator windings one upon each of the two third cores of the core structures and cross connected so that each is connected to the second. operative side of the current.

magnifying device whereof the first said operative side is connected to the booster winding on the other magnetic core structure, substantially as described.

3. lin a telephonie repeater, the combination of a current-magnifying device, a

magnetic core structure comprising three cores magnetically in parallel with one'another between two yokes common to the two sets of concurrent ends of the cores, two line-windings, one upon each ofy two said cores, of which said line-windings one is connected to an arti'cial line and the other is connected to the speech-line in series with a condenser, a booster winding in two equal halves in series to assist one another, each mounted upon one of the said two cores which carry line-windings and having their two tree ends connected to one operative side ot the said current-magnifying device, a generator winding mounted on the third said core of the said core structure and connected to the other operative side of the currentmagnifying device, substantially as described.

aln a telephonie repeater, the combination of a 'currentmagnifying device, a magnetic core structure comprising three cores magnetically in parallel with one another between two yokes common to the two sets of concurrent ends of the cores, two linewindings, one upon each of two said cores, whereof one is ,connected to an artificial line and the other is connected to one speechline, a third line-winding connected to a speech-line andA mounted on the same core as that which carries the winding of the first said 'speech-line, a booster winding in two equal halves in seriesto assist one another, each mounted upon one of the said two cores which carry line-windings and having their two free ends connected toene operative side of the said current-magnifying device, a

generator winding mounted on the third said core of the said core structure and connected to the other operative side of the current-magnifying device, substantially as described.

5. lln a telephonie repeater, the combination of a current-magnifying device, a magnetlc core structure comprislng three cores lying side by side in substantially one plane extending between' two yokes magnetically common to the two sets of concurrent ends of the cores and of which cores the continuity of each of the two outer ones is interrupted by an air-gap, two line-windings, one upon each of the. said two'outer cores,1 a booster winding in two equal halves in se- MND ries to assist one another, each half mounted upon one of the said two out/er cores and having their two free ends connected to one operative side of the said current-magnifying device, a generator winding mounted on theeenter coreof the said three and connected tothe other operativel side of the current-magnifying device, substantially as described.

6.' in a telephonie repeater, the combinanationv of a thermionic valve, a magnetic core structure comprising three cores magnetically in' parallel with one another between two yohes common to the two sets of concurrent ends of the cores, two line-windings, one upon each of two said cores, a booster winding in two equal halves in series to assistl one another, each mounted upon one of the said two cores which carry linewindingsA and. having their two free ends connected to one operative side ot the said thermionic Lvalve, a generator winding mounted on the third said core of the said .core structure and 'connected to the other l lbetween two yokes common to the two sets operative side of the thermionic valve, substantially as described.

1,7. Ina telephonie repeater, thelconibina` tion of two thermionic valves, two magnetic core structures, each comprismg three cores magnetically in parallel with one another of concurrent endsof the cores,'two line'- wlndmgs, one upon each of twov cores of the one "said core structure, ytwo 11ne- 'windings one upon each of two 4cores of the l other sal core structure, a booster winding in two equal halves in series connected to assist one another, each said halfmounted upon one of the two cores which carry linewlndings on the one ma -netic core structure and havingv theirtwofyee en ds connected to one operatwe side ofmne said thermlomc valve, a similar booster wmdlng on the mames@ correspondin two cores of the other core structure an having its free ends connected.

to the corresponding operative sideof the thermionic valve, two generator wmdins one upon each of thetwo third cores of t e core structurea` and cross connected so that each is connected to the second operative side of 'the thermionic valve, whereof the rst said operative side is connected to the booster winding on the other mafgnetic core structure, substantially as set orth.

In testlmony whereof we have signed our I names to this specification in the presence of two subscrlbmg wltnesses. 

